Casting core for turbine engine components and method of making the same

Abstract

A turbine engine component, such as a turbine blade or vane, with complex internal features can be cast using a core having a first region with normal resolution features and a second region with high resolution features. The core can be formed from a single structure. Alternatively, the first region can be defined by a first ceramic core piece, which can be formed by any conventional process, such as by injection molding or transfer molding. The second region can be defined by a second ceramic core piece formed separately by a method effective to produce high resolution features, such as tomo lithographic molding. The first core piece and the second core piece can be joined by interlocking engagement, such as by male and female dovetails. The high resolution features can be effective to produce high efficiency internal cooling features in the cast component.

1 . A method of forming a core for use in casting a turbine engine component comprising:
 forming a normal resolution region of the core; and   forming a high resolution region of the core using a method effective to produce high resolution features.   
     
     
         2 . The method of  claim 1  wherein the normal resolution region is defined by a first core piece and the high resolution region is defined by a second core piece, and
 further including the step of joining the first and second core pieces. 
 
     
     
         3 . The method of  claim 2  wherein the first core piece includes a passage therein, wherein the second core piece includes a protrusion, wherein the protrusion includes a first portion and a second portion, wherein the first portion is configured to be received in the passage and the second portion is configured to prevent receipt into the passage, wherein the joining step results in only the first portion of the protrusion being received in the passage, whereby a spacing between the first and second core pieces is maintained, and further including the steps of:
 heating the first portion of the protrusion; and 
 forming the first portion of the protrusion such that the first and second core pieces are in interlocking engagement. 
 
     
     
         4 . The method of  claim 2  wherein the first core piece includes a plurality of recesses and the second core piece includes a plurality of protrusions, wherein the recesses and the protrusions are configured for interlocking engagement, wherein the joining step results in each protrusion being received in a respective one of the recesses. 
     
     
         5 . The method of  claim 2  wherein during in joining step, both the first core piece and the second core piece are fully fired. 
     
     
         6 . The method of  claim 2  wherein during in joining step, both the first core piece and the second core piece are in a green state. 
     
     
         7 . The method of  claim 2  wherein the joining step is performed outside of a mold. 
     
     
         8 . The method of  claim 2  wherein the first core piece includes a recess and further including the steps of:
 forming the second core piece with a foil member, wherein a portion of the foil member is embedded in the second core piece and a portion of the foil member protrudes beyond the second core piece; 
 wherein the joining step comprises inserting the protruding portion of the foil member into the recess of the first core piece. 
 
     
     
         9 . The method of  claim 1  wherein the core is a multi-wall core. 
     
     
         10 . The method of  claim 1  further including the steps of:
 forming a core print separately from the core; and 
 joining the core print to the core. 
 
     
     
         11 . A method of joining a multi-piece core for a cast airfoil comprising:
 forming a first ceramic core piece, the first core piece being shaped as an airfoil body portion and having one of a plurality of recesses and a plurality of protrusions, the first core piece including an engaging surface;   separately forming a second ceramic core piece having a high resolution region, the second core piece having an engaging surface, the second core piece having an opposite one of a plurality of protrusions and a plurality of recess, the recesses and the protrusions of the first and second core pieces being configured for substantially interlocking engagement, the second core piece shaped as a trailing edge portion of an airfoil; and   joining the first core piece and the second core piece such that each protrusion is received in a respective recess and such that the engaging surfaces abut, whereby a core assembly is formed.   
     
     
         12 . The method of  claim 11  wherein during joining step, both the first core piece and the second core piece are in a green state. 
     
     
         13 . The method of  claim 11  wherein the joining step is performed outside of a mold. 
     
     
         14 . The method of  claim 11  wherein the first core piece includes a recess and further including the step of forming the second core piece with a foil member, wherein a portion of the foil member is embedded in the second core piece and a portion of the foil member protrudes beyond the engaging surface of the second core piece; and wherein the joining step comprises inserting the protruding portion of the foil member into the recess of the first core piece. 
     
     
         15 . The method of  claim 11  wherein at least one of the first core piece and the second core piece is a multi-wall core. 
     
     
         16 . The method of  claim 11  further including the steps of:
 forming a core print separately from the first and second core pieces; and 
 joining the core print to at least one of the first core piece and the second core piece. 
 
     
     
         17 . The method of  claim 11  wherein at least a portion of the first ceramic core piece is made using a method effective to produce high resolution features. 
     
     
         18 . The method of  claim 11  wherein the step of separately forming the second ceramic core piece is performed using a method effective to produce high resolution features. 
     
     
         19 . A casting core for a turbine engine component comprising:
 a ceramic core body having a first region of normal resolution detail and a second region of high resolution detail.   
     
     
         20 . The casting core of  claim 19  wherein the first region is an airfoil body portion and the second region is an airfoil trailing edge portion. 
     
     
         21 . The casting core of  claim 19  wherein the first region is defined by a first core piece and the second region is defined by a separate second core piece. 
     
     
         22 . The casting core of  claim 19  wherein the core body is a multi-wall core. 
     
     
         23 . The casting core of  claim 19  further including a core print formed separately from but attached to the ceramic core body.